Realing us in

Why do men say at the beginning of a relationship that you'll move in with them or you will get an apartment together but when the deadline is near and then all of a sudden they change their minds. Men and women, it's not just us but 90% of the time it's the men. What are they thinking? Are they just trying to real us in at the beginning by saying all these things then once they have us (or they think they have us) they become an entire new person?